The present invention relates to a combined surgical needle suture device and, more particularly, to such a device in which a shrinkable tubing attaches a braided suture of particular construction to a surgical needle.
For many years, surgeons have employed combined surgical needle-suture devices in which a suture, or ligature, is attached to the shank end of a surgical needle. Such needle-suture combinations are provided for a wide variety of monofilament and braided suture materials, both absorbable and non-absorbable, e.g., catgut, silk, nylon, polyester, polypropylene, linen, cotton, and absorbable synthetic materials such as polymers and copolymers of glycolic and lactic acids and their cyclic dimers, glycolide and lactide.
Needle-suture combinations fall into two general classes: standard, or non-detachable, needle attachment and removable, or detachable, needle attachment. In the case of standard needle attachment, the suture is securely attached to the needle and is intended to be inseparable therefrom except by deliberate cutting or severing of the suture. Removable needle attachment, by contrast, is such that the needle is separable from the suture in response to a pulling or rupture force exerted by the surgeon. Minimum acceptable forces required to separate a needle from a suture (for various suture sizes) are set forth in the United States Pharmacopeia (USP). The USP prescribes minimum individual pull-out forces and minimum average pull-out forces as measured for five needle-suture combinations. The minimum pull-out forces for both standard and removable needle-suture attachment set forth in the USP are hereby incorporated by reference.
One typical method for securing a suture to a needle involves providing a cylindrical recess, or axial bore, in the shank end of a needle and securing a suture therein. For example, U.S. Pat. No. 1,558,037 teaches the addition of a cement material to such a substantially cylindrical recess to secure the suture therein. Additional methods for bonding a suture within a needle bore are described in U.S. Pat. No. 2,928,395 (adhesives) and U.S. Pat. No. 3,394,704 (bonding agents). Alternatively, a suture may be secured within an axial bore in a needle by swaging the needle in the region of the recess. See, e.g., U.S. Pat. No. 1,250,114. Additional prior art methods for securing a suture within a needle bore include expansion of a catgut suture through the application of heat (U.S. Pat. No. 1,665,216), inclusion of protruding teeth within the axial bore to grasp an inserted suture (U.S. Pat. No. 1,678,361) and knotting the end of the suture to be inserted within the bore to secure the suture therein (U.S. Pat. No. 1,757,129).
Methods for detachably securing a suture to a needle are also known. For example, U.S. Pat. Nos. 3,980,975 and 3,980,177 teach swaging a suture within a needle bore such that the suture will have a pull-out value of from 3 to 26 ounces. Other detachable needle-suture attachment methods include providing a weakened suture segment (U.S. Pat. No. 3,949,756), tipping the end of a suture to be inserted in the axial bore of a needle with a lubricant (U.S. Pat. No. 3,963,031) and pre-tensioning a suture that is swaged within an axial needle bore (U.S. Pat. No. 3,875,946). See also, U.S. Pat. Nos. 3,799,169, 3,880,167, 3,924,630, 3,926,194, 3,943,933, 3,981,307, 4,124,027 and 4,127,133.
Another method for attaching a suture to a needle involves the use of a tubing which is secured to the shank end of the needle and to the suture. For example, U.S. Pat. No. 1,613,206 describes the use of a tubing (preferably silver) which is secured to the shank end of a needle and to a ligature. It is suggested that the tube may be attached to the needle by pressure or soldering and to the ligature by pressure or cementing. It is further suggested that the shank of the needle be of reduced cross section and that the furthest extremity of the reduced diameter shank section be provided with a spike or point upon which the suture may be secured prior to tube application.
U.S. Pat. No. 2,240,330 describes a tubing attachment method whereby the tubing and suture are releasably secured to the needle. In particular, the needle and tubing are provided with cooperating catch and abutment means which are released one from the other by rotating the needle 90.degree. relative to the tubing (or vice versa). The tubing is manufactured from spring-tempered carbon steel or chrome nickel steel and is secured to the suture by heating the tubing and then swaging to the suture.
U.S. Pat. No. 3,311,110 relates to a flexible composite suture having a tandem linkage. The needle is secured to a flexible suture leader manufactured from a readily sterilizable plastic such as nylon, linear polyethylene, isotactic polypropylene, polyester, silk or other proteinaceous material, e.g., by inserting and crimping the suture leader within an axial bore in the needle shank. The opposite end of the suture leader is crimped within a connector sleeve of a thin walled metal tubing, e.g., stainless steel. The opposite end of the tubing is crimped around a stiff suture, e.g., monofilament stainless steel.
U.S. Pat. No. 3,918,455 to Coplan describes a needle-suture attachment wherein a hollow suture portion is secured to the shank end of a needle which is of reduced cross-section compared with the remainder of the needle.
Additional patents which describe the use of a tubing to effect suture-needle attachment include U.S. Pat. Nos. 4,672,734 (forming needle from U-shaped metal plate around suture), 4,359,053 (silicone tubing), 3,835,912 (laser welding of metal tube to needle), 2,814,296, 2,802,468 (chamfered tubing ends), 2,302,986, 2,240,330, 1,981,651 (needle and tubing screw threaded), 1,960,117, and 1,591,021.
Numerous disadvantages exist with methods used heretofore to effect needle-suture attachment. For example, those methods which involve the formation and use of an axial bore in the shank end of the needle require the use of expensive hole forming equipment. Moreover, it is difficult to maintain the bore concentric with the center-line of the needle and to control the depth (and diameter) of the bore when drilling the needle shank, whether using conventional drilling equipment or laser drilling. Another disadvantage lies in the possibility that foreign substances may inadvertently or uncontrollably be introduced into the needle bore, e.g., oil employed in the bore-drilling operation or silicone employed in a needle siliconization process. Measures taken to prevent or minimize the introduction of foreign materials into the needle bore, e.g., water blocking during the needle siliconization operation, are inconvenient adding time, effort and cost to the needle production process.
Attachment processes which employ bored needle shanks also limit the range of materials from which needles may be fabricated in a cost effective fashion. For example, it is exceedingly difficult to drill Series 300 stainless steel (laser drilling is required) and, once drilled, it is difficult to swage Series 300 stainless steel in a consistent and reliable manner. For this reason, Series 300 stainless steel is not employed for the vast majority of needled suture products despite its advantageous combination of strength and ductility characteristics as compared to conventionally employed Series 400 stainless steel.
Additional disadvantages associated with needle-suture attachment methods which employ bored needle shanks include the weakness imparted to the bored section of the needle, particularly after swaging, and the attendant increased possibility that the needle will fracture in this region. It is also difficult to provide a specialized surface finish to the needle shank to assist in needle attachment, e.g., a texturized surface and/or a tapered bore. Swaging equipment used in such needle-suture attachment methods is also maintenance intensive.
Needle-suture attachment methods which have employed tubings heretofore also exhibit numerous disadvantages. Methods which employ metal tubings greatly diminish the flexibility of the needle-suture combination in the attachment region. Such diminished flexibility has a deleterious effect in many surgical procedures. Swaging of the tubing to the needle and the suture is also undesirable in that swaging is time-consuming, maintenance intensive, and subject to variability in attachment force.
Moreover, needle-suture attachment methods which have employed tubings heretofore have necessarily required the use of tubing having an inner diameter essentially equal to the outer diameters of the needle shank and suture tip to be attached. Too large a difference between the aforesaid inner and outer diameters inhibits the attachment process and presents a tight, secure interface between needle (and/or suture) and tubing. The limited tolerance between the tubing inner diameter and the needle shank/suture outer diameters in such methods make these dimensions critical thereby making the attachment process more difficult and time-consuming and increasing the likelihood of attachment failure and/or rejected materials.
In addition to the foregoing deficiencies associated with known needle-suture attachment methods and the resulting needle-suture devices, the sutures themselves, when they are of multifilament construction, tend to exhibit disadvantages of their own. While currently available braided suture products are generally acceptable in terms of their knot-tying and knot-holding properties, as removed from the package, they tend to be stiff and wiry and retain a "set" or "memory" such that at the time of use, it is usually necessary for the surgeon or assistant personnel to flex and stretch the suture to make it more readily handible. Furthermore, the surfaces of known braided sutures are perceptibly rough. Thus, if one passes one's hand or fingers along the braid, surface irregularities will be readily detected. The result of this rough surface is that the suture will exhibit drag or chatter as it is drawn through tissue, characteristics which militate against smooth, neat, accurately placed wound approximation so necessary to excellence in surgical practice.
In the case of one braided suture now on the market, due to the necessity of having to meet fiber strength requirements while at the same time retaining acceptable knot-tying and knot-holding properties, the suture is constructed from a greater amount of fiber and consequently is of larger diameter than the accepted industry standard.
Accordingly, it is an object of the present invention to provide a surgical needle-braided suture attachment procedure which eliminates the need for drilling a bore in the needle shank and swaging the suture therein.
It is also an object of the invention to provide an attachment procedure which reliably secures the suture to the needle in an efficient manner without close tolerances between elements.
It is a further object to provide a surgical needle-suture attachment procedure which is flexible and atraumatic.
An additional object of the invention is to provide a combined surgical needle-braided suture device wherein separation of the needle from the suture is obtained by pulling the suture from the needle within a predetermined range of pull-out force.
Another particular object of this invention is to provide a combined surgical needle-braided suture device in which the braided suture component exhibits significantly reduced tissue drag compared with that of a comparably sized braided suture of known, or standard, construction.